1. Field of the Invention
The present invention relates to a toner cartridge, for use in an image forming apparatus that forms an electrostatic latent image and develops the electrostatic static latent image into a visible image, an image drum unit (ID unit) to which the toner cartridge is detachably mounted, and an image forming apparatus.
2. Description of the Related Art
An electrostatic latent image is formed on a photoconductive drum, and is developed in an ID unit into a toner image. Electrophotographic printers such as LED printers frequently make use of a replaceable consumable which is in the form of a toner cartridge.
A toner cartridge is formed with a discharge opening through which toner is discharged. The toner cartridge is attached to the ID unit such that the discharge opening is in alignment with a receiving opening formed in the ID unit. Then, a shutter or a seal of the toner cartridge is opened, the toner is discharged from the discharge opening into the ID unit. The properties of toner determine the design factors such as toner type; the specifications of rollers and a member for controlling a thickness of a toner layer; printing speeds; the conditions for applying high voltages; and the temperature settings of a fixing unit may be dependent. Therefore, if toner not designed for use in the ID unit is replenished, printing results is poor, or jamming of paper occurs due to the fact that non-fused toner adhering to a fixing roller.
In order to prevent the aforementioned drawbacks, a toner cartridge may be equipped with a memory element that holds information on the toner held in the toner cartridge. When the toner cartridge is attached to the ID unit, the information on the toner may be read into an image forming apparatus. When a toner cartridge holding an unacceptable toner is mounted to the ID unit, a warning or message may be displayed to a user on a liquid crystal display (LCD). Data communication between the memory element and the image forming apparatus is of two types: a contact type and a non-contact type. For the contact type, a proper pressure between a contact area of the memory element and a contact area of the image forming apparatus may not be ensured due to dimensional errors within tolerances, preventing good electrical connection from being made. Japanese Patent Application Laid-Open No. 2002-169365 discloses a structure for solving such a problem. That is, contact areas are provided at locations of the image forming apparatus where the toner cartridge is pressed against the ID unit. The contact areas make electrical continuity.
When the toner cartridge is mounted to the ID unit, the toner cartridge should be pressed against the ID unit with a force more than necessary for making electrical connection. This relatively large force may cause scratches and/or damage to the contacts when the toner cartridge is mounted or dismounted. Scratches and damage prevents the toner cartridge from being recycled.